Insight on sleep training a 4 month old?

Baby will be 4 months next week, don’t really have a set schedule on time I usually follow her wake windows and always try to get her to nap after 2 hours if she even makes it that long. Naps are always capped at 2 hours if she sleeps that long. We’re always up and out of bed by 9am and start bedtime routine between 8-9pm.
She has HATED her bassinet since night one, literally. We’ve resorted to cosleeping or sleeping in her swing. I know it’s horrible and not safe sleep AT ALL. Which is why I really would like to try sleep training as soon as I can when she’s 4 months.
Cosleeping she wakes up frequently looking to nurse. She’ll last all night in her swing though until 6-7am, wakes up happy and will eat then fall back asleep with me until 9am. With that being said, I believe(?) she can go all night without being hungry, waking to eat may just be a comfort thing? I’m not sure.
I’m very nervous to sleep train because I don’t want to hear my baby cry like that. But I also know she has to learn the skill and I want her sleeping safely not in a swing. I’d like to try Ferber first, possibly resort to CIO if Ferber isn’t working. I’m also wondering if I can put my husband in charge of check-ins?
Can I just hear some advice from parents who’ve done this before? Maybe some affirmations I can tell myself so I don’t give up sleep training because of her crying. I’m a nervous wreck about it and what’s to come.